Pipe coupling

ABSTRACT

A pipe coupling flange ( 16 ) comprising a central bore and having first and second ports for receiving valves and a plurality of channels, wherein a take-off channel links the first port with the central bore, a feed channel links the first port directly or indirectly with the second port; and wherein the second port links directly or indirectly with the exterior of the flange. Across two pipe flanges ( 16 ), an fixed directly to the periphery of each flange there may be a Bridge ( 30 ). The bridge ( 30 ) may be capable of having process media ( 24 ) monitoring devices fixed directly to it.

The present invention relates to pipe couplings and in particular toflanged-pipe couplings of the type, which comprise a bolted pipe joints.

Flanged pipe couplings are commonplace on manufacturing plant (e.g.chemical plant) since they provide a relatively simple way of securingsections of process pipe work to one another.

The monitoring of process conditions inside a process pipe can be ofparamount importance in controlling the manufacturing and ordistribution process. Accordingly, transducers can be fitted to processpipe work to enable test and measurement of the fluid to take placein-situ.

A common measurement transducer is the differential pressure (or “ΔP”)transducer, which is used for measuring pressure differentials that canrelate to a number of fluid properties including viscosity and flowrate.

Current methods of process pipe media monitoring for DifferentialPressure Flow Measurement (DPFM) involve:

1) Hanging all necessary valves and/or manifolds and process mediamonitoring devices from two screwed or welded fittings, which are fixedto the periphery of traditional flanges known as “orifice flanges”.These flanges are bolted together about a traditional orifice plate andgaskets from which a differential pressure is created.

2) Using tube or pipes (commonly referred to as Impulse Lines) toconnect the two screwed or welded fittings to the valve and/or manifoldassemblies which are located some distance away from the orifice flangesand pipe work.

3) Cutting into the main process pipe and manufacturing traditional“Flanged Pipe Tee's”. From the leg of the pipe tee, flanged valves ormanifolds are connected while process media monitoring devices areconnected using tube and fittings or further flanged joints.

A typical prior art DPFM assembly incorporating a ΔP transducer is shownin FIG. 2 of the accompanying drawings, whereby a sample of the fluid inthe process pipe is taken at either side of a partial obstruction, inthis case, an orifice plate located between the process pipe flanges.The transducer is protected by a “double block and bleed” (DBB) valveassembly, which is primarily a safety device, but which has other usesin servicing of the flanged joint, transducer and associated pipe work.

Disadvantages of prior art DPFM assemblies include:

1) Excessive weight on the two screwed or welded fittings in the OrificeFlanges. These joints may be subject to failure due to bending moments,vibration and or corrosion.

2) Space-inefficiency

3) A typical DPFM assembly comprises a large number of pipes, nipples,fittings and valves, all of which need to be sealed. Moreover, becausedifferential pressure measurements are highly complex and require anumber of joints to build up an assembly, the risk of process leakage toatmosphere is increased. If there is a leak in any of the seals, thenprocess fluids may escape to atmosphere, which is potentially hazardousto persons nearby, harmful to the environment and wasteful.

4) Because there are a number of exposed pipes and fittings, theassembly is susceptible to being knocked and damaged. Moreover,engineers or operators when working or maintaining the plant sometimesuse the take-off pipes as “steps”. Because the assembly is largelyunsupported, except by the nipples where the first take-off pipe emergesfrom the flange, it is highly susceptible to bending and/or shearloading, for which it was not designed.

5) The failure of any of the joints, especially the joint between theprocess pipe and the first block valve, can be catastrophic, forexample, where the process media is a boiling acid.

6) The pipes, fittings, valves and transducer are mounted away from theprocess pipe, which creates a “dead leg”, that is to say, a volume offluid between the process pipe and the transducer that is stagnant. Thisintroduces a number of problems for example; bleeding the DBB assemblywastes unnecessarily large quantities of process fluid; the fluidconditions, for example, the temperature, at the transducer may not bethe same as those in the process pipe itself, and the take-off pipes andfittings may become contaminated. Furthermore, the accuracy of readingstaken from such installations may be reduced due to length of “Impulselines” and the quality of workmanship.

7) The DPFM assembly needs to be assembled and installed on-site becauseit is not possible to ship it pre-fabricated, being a bespoke item.

8) The installation of an assembly is costly and time consuming owingto:

-   -   a) The complexity of the set-up, the number of parts involved        and the need for specialist engineers to install and test the        assembly.    -   b) The complex build up of additional support work along with        the valve and/or manifold assemblies;    -   c) The labour intensive assembling process required to install        the additional tube and/or pipe work and fittings, along with        the valve/manifold and process media monitoring device; and    -   d) The fabrication process required making up the “Flange Tee's”        and subsequent interconnecting feeds.

It is therefore an object of the present invention to propose a solutionto one or more of the above problems. In particular, it is an object ofthe invention to provide a pipe coupling assembly which is a safer, morereliable and more cost efficient method of fixing process mediamonitoring devices to process pipe work.

Accordingly, a first aspect of the invention provides a pipe couplingflange comprising a central bore and having first and second ports forreceiving valves and a plurality of channels, wherein a take-off channellinks the first port with the central bore, a feed channel links thefirst port directly or indirectly with the second port; and wherein thesecond port links directly or indirectly with the exterior of theflange.

The pipe coupling flange of the invention may additionally comprise athird port connected directly or indirectly with the first port via oneor more feed channels.

The above-mentioned indirect connections may comprise one or morechannels found in the pipe flange.

The third port may be adapted to receive an in-line valve, which may beattached to a vent pipe.

Alternatively, the pipe coupling flange may be provided with a fourthport adapted to receive a pipe joint and a feed channel connecting thethird port with the fourth port.

In a preferred embodiment of the invention, the ports of the pipecoupling flange are adapted to receive rising stem valves.Alternatively, however, the ports may be adapted to receive in-linevalves.

The invention is preferably adapted to receive a transducer, which isconnected directly or indirectly, to a port of the pipe coupling flange.The transducer may be connected directly to the pipe coupling flange orit may be connected indirectly, by way of a bridge element.

Additionally, the bridge may comprise one or more ports and channels forreceiving valves or blanks.

The bridge may be manufactured of any suitable material, although it isenvisaged that a metal would be most preferable. The bridge may befabricated such that it is adapted to receive industry standardtransducers. Accordingly, an industry standard footprint is mostpreferably incorporated into the design of the bridge.

The flange of the pipe coupling preferably has one or more throughapertures to enable adjacent flanges to be connected to one another.Most preferably, the through apertures are adapted to receive bolts.

The flanges may be manufactured of any suitable material, althoughmetal, and in particular steels and stainless steels, may be appropriatein certain circumstances.

The flanges may be formed integrally with a process pipe or may comprisecollar elements. Where collar elements are provided on the flanges, theyare preferably adapted to slidably engage with a process pipe. Where theflanges comprise collar elements, the collar elements are preferablyadapted for welded connection to the end of a process pipe.

The pipe coupling flange of the invention may be used to provide a blockand bleed outlet on a process pipe. Where a third port is provided, thepipe coupling flange of the invention may provide a double block andbleed outlet on the process pipe. It is envisaged that two pipe couplingflanges according to the invention will be used together to provide DPFMassembly integrally with the process pipe.

Where two pipe coupling flanges according to the invention are used toprovide a DPFM assembly, an orifice plate is preferably positionedbetween them to create a partial obstruction in the process pipe.

A transducer is preferably fitted across the DPFM assembly, which isformed using a pair of pipe couplings according to the invention. Thetransducer is preferably affixed to the DPFM assembly by way of a bridgeor interface block. The bridge preferably has one or more channelstherein that connect the outlet channels of the pipe coupling with theinlet ports of the transducer.

The transducer, where provided, may be a pressure sensor or adifferential pressure sensor. All joints and/or interfaces arepreferably sealed using gaskets.

According to a second aspect of the present invention there is provideda pipe coupling comprising of two bolted pipe flanges, rising stem typevalves, an interconnecting “Bridge”, an orifice plate and pipe gasketsor rings. Thus allowing the installation of process media monitoringdevices directly on to the process pipe work.

The pipe flanges may incorporate valves of the rising stem type. Aninterconnecting bridge is preferably fixed directly to the periphery ofthe flanges, which may provide independent process pipe media feeds fromeach of the two flanges. The bridge may also facilitate the directfixing of process media monitoring devices.

The pipe coupling assembly is preferably manufactured of metal alongwith suitable gasket materials (for example, metal, graphite orcompressed fibres) for a traditional pipe flange joint build up. In amost preferred embodiment of the invention, the coupling assembly iscompliant with any necessary design codes for valves, manifolds, flangesand pipe work.

It is envisaged that the pipe couplings of the invention may be suppliedin kit form. The kits may comprise one or more pipe couplings, one ormore orifice plates and optionally a transducer. The transducer suppliedwith the kit may be a differential pressure sensor.

Where the invention is provided in kit form, it is preferablypre-assembled and pressure tested.

A preferred embodiment of the invention shall now be described, by wayof example only, with reference to the accompanying drawings in which;

FIG. 1 shows cross-section through a flanged pipe coupling;

FIG. 2 shows a perspective view of a prior art differential pressuregauge arrangement fixed across a flanged pipe coupling;

FIG. 3 a shows a side elevation of a coupling according to theinvention;

FIG. 3 b shows an end elevation of a pipe coupling according to theinvention;

FIG. 4 shows a cross-section of FIG. 3 a on X-X;

FIG. 5 shows an alternative cross-section of FIG. 3 a on X-X; and

FIG. 6 shows a cross-section of FIG. 3 b on Y-Y.

Referring to FIG. 1 of the drawings, a bolted pipe joint 12 is shown inwhich, a pair of adjacent pipes 14 are secured to one another by way ofbolts 18 that pass through apertures in flanges 16 located at the endsof the pipes. There is an apertured orifice plate 20 clamped between theflanges 16. The aperture 22 in the orifice plate 20 is tapered in theflow direction of fluid in the pipe 14, as indicated by arrow A. Asfluid flows through the pipe 14, it is restricted by the orifice plate20. Accordingly, there is a region B of increased fluid pressureupstream of the orifice plate 20 and conversely, a region C of reducedfluid pressure downstream of the orifice plate 20.

A pressure differential “ΔP” transducer can be fitted across the orificeplate 20 to compare the fluid pressure upstream and downstream of theorifice plate 20 to determine the flow characteristics of the fluid.

FIG. 2 of the drawings shows a prior art method of affixing a ΔPtransducer assembly 10 across an orifice plate 20 in which, a pair ofadjacent process pipes 14 are jointed as detailed above.

Each of the pipe flanges 16 have been drilled and tapped to receive ascrew-threaded or welded nipple 22. The ΔP gauge assembly 10 isprotected by a “double block and bleed” valve assembly, enabling on theone hand, the transducer 24 to be selectively isolated from the processpipe 14, and on the other, the connecting pipe work to be “bled” as andwhen required.

Accordingly, the take-off pipes 26 are fitted with a “primary block”valve 28, which isolates the assembly 10 from the process pipes 14. Thetake-off pipes 26 then lead towards an interface block 30, which has a“secondary block” valve 32 incorporated therewith. There is alsopresent, located between the primary 28 and secondary 32 block valves, avent pipe 34, incorporating a “vent” valve 36.

With the primary 28 and secondary 32 block valves open and the ventvalve 36 closed, the transducer 24 is able to sample the pressure in theprocess pipe 14 at either side of the orifice plate 20. After use, theprimary 28 and secondary 32 block valves can be closed, and the ventvalve 36 opened to drain the take-off pipes 26.

Furthermore, with the secondary block valve 32 closed, the transducer 24may be removed for servicing, cleaning or replacement.

Turning now to FIGS. 3 a and 3 b, the pipe coupling 10 comprises of twobolted pipe flanges 16 with an interconnecting bridge 30 fixed directlyto the periphery of the two flanges 16. The two flanges 16 can be bolted18 together about a traditional orifice plate 20 and flange gaskets. TheBridge 30 facilitates the direct fixing of process media monitoringdevices 24 and may incorporate additional ports and/or valves.

The Bridge 30 also allows the two independent process media feeds to bedirected to the process media monitoring device 24. The Bridge 30 allowsfor opposing lateral movement of the flanges 16 when the orifice plate20 requires replacing. The two flanges 16 can be separated without theneed to disassemble the complete coupling 10.

As shown in FIG. 3 b rising stem valves 28, 32 and 36 are also fixed tothe periphery of each of the pipe flanges 16. These valves can bearranged to provide the process media control functions required. TheBridge 30 can also facilitate additional rising stem valves and/or portsif required.

In FIGS. 3 a and 3 b, a ΔP transducer assembly 10 according to theinvention is shown whereby the “double block and bleed” valve assemblyis formed integrally with the process pipe flanges 16. The ΔP transducer24 is connected to an interface block 30, which bolts directly to amachined “flat” 38 on the flange 16 of the process pipe 14. Each flange16 comprises a primary 28, secondary 32 and bleed 36 valve in additionto means for the attachment of a vent pipe 34 (not shown). The operationof the assembly 10 is the same as for a conventional assembly, that isto say; opening the primary 28 and secondary 32 block valves and closingthe vent valve 36 for normal operation; or closing the primary 28 whilstopening the secondary 32 block valve and vent valve 36 to bleed theassembly 10.

FIG. 4 shows a section of flange 16 of the invention. The flange 16 hasa central bore 42, through which the process fluid flows and boltapertures 40 for connecting adjacent flanges 16 to one another.

The take-off channel 26 leads to a primary block valve seat 44, which isadapted to receive a rising stem valve (not shown for clarity) forisolating the process fluid from the transducer (not shown). A firstfeed channel 46 leads from the primary block valve seat 44 to asecondary block valve seat 48, which is adapted to receive a rising stemvalve. A second feed channel 50 leads from the secondary block valveseat 48 to a port 51. The bridge and transducer (not shown) are fitteddirectly to the machined flat face 52 of the flange 16.

A third feed channel 54 leads from the primary block valve seat 44 tothe vent valve seat 56, which is, adapted to receive a rising stem valve(not shown). Finally, a fourth feed channel 58 leads from the vent valveseat 56 to a bleed pipe nipple seat 60, which is used for connecting ableed pipe (not shown) to the assembly 10.

FIG. 5 shows an alternative embodiment of the invention whereby thefourth feed channel 58 and bleed pipe nipple seat 60 are replaced by anin-line bleed valve and pipe connector 62, to which the bleed pipe 34 isdirectly fitted.

Finally, FIG. 6 shows a section through the pipe flanges and bridge 30.The second feed channel 50 leads into channels 64 in the bridge 30 thatcorrespond therewith. The bridge 30 is seated on a seal or seals 66 andis affixed thereto by bolts 68. The transducer 24 is affixed to thebridge 30 using an industry standard connector (not shown).

1. A pipe coupling flange comprising a central bore and having first andsecond ports for receiving valves and a plurality of channels, wherein atake-off channel links the first port with the central bore, a feedchannel links the first port directly or indirectly with the secondport; and wherein the second port links directly or indirectly with theexterior of the flange.
 2. A pipe coupling flange as claimed in claim 1further comprising a third port connected directly or indirectly to thefirst or second port via one or more feed channels.
 3. A pipe couplingas claimed in claim 1, wherein the pipe coupling is provided with afourth port adapted to receive a pipe joint and a feed channelconnecting the third port with the fourth port.
 4. A pipe couplingflange as claimed in claim 1, wherein the ports of the pipe coupling areadapted to receive rising stem valves.
 5. A pipe coupling as claimed inclaim 1, wherein the ports are adapted to receive in-line valves.
 6. Apipe coupling flange as claimed in claim 1, further comprising atransducer.
 7. A pipe coupling flange as claimed in claim 6, wherein thetransducer is connected to an outlet channel of the pipe coupling.
 8. Apipe coupling flange as claimed in claim 6, wherein the transducer isconnected directly to the pipe coupling.
 9. A pipe coupling flange asclaimed in claim 6, wherein the transducer is connected to the pipecoupling indirectly by way of a bridge element.
 10. A pipe couplingflange as claimed in claim 9, wherein the bridge is manufactured ofmetal.
 11. A pipe coupling flange as claimed in claim 10, wherein thebridge is manufactured of steel.
 12. A pipe coupling flange as claimedin claim 9, wherein the bridge is adapted to receive industry standardtransducers.
 13. A pipe coupling flange as claimed in claim 9, whereinthe bridge incorporates an industry standard footprint for receiving atransducer.
 14. A pipe coupling flange as claimed in claim 1, when theflange is formed integrally with a process pipe.
 15. A pipe couplingflange as claimed in claim 1, when the flange comprises a collarelement.
 16. A pipe coupling flange as claimed in claim 15, wherein thecollar element is adapted to slidably engage with a process pipe.
 17. Apipe coupling flange as claimed in claim 15, wherein the collar elementis adapted for welded connection to a process pipe.
 18. A pipe couplingassembly comprising two adjacent pipe coupling flanges as claimed inclaim
 1. 19. A pipe coupling assembly as claimed in claim 18, furthercomprising an orifice plate located between the adjacent pipe couplingflanges.
 20. A pipe coupling assembly as claimed in claim 18, furthercomprising a bridge and a transducer, the bridge having channels thereinfor connecting at least one port of the at least one pipe couplingflanges with the inlet ports of the transducer.
 21. A pipe couplingassembly as claimed in claim 20, wherein the transducer is adifferential pressure sensor and the bridge has channels that connect atleast one port of each pipe coupling flange with a respective port ofthe transducer.
 22. A pipe coupling comprising of two bolted pipeflanges, rising stem type valves, an interconnecting “Bridge”, anorifice plate and pipe gaskets or rings, which allows the installationof process media monitoring devices directly on to the process pipework.
 23. A kit of parts comprising; one or more a pipe coupling flangescomprising a pipe with a central bore having a flange integrally formedtherewith, the flange having first, second and third ports for receivingvalves and a plurality of channels, wherein a take-off channel links thefirst port with the central bore, feed channels link the first portdirectly or indirectly with the second and third ports; and wherein thesecond and third ports link directly or indirectly with the exterior ofthe flange; and a bridge having one or more channels therein forconnecting at least one port of the at least one pipe coupling flangeswith a transducer.
 24. A kit of parts as claimed in claim 23 furthercomprising a transducer.
 25. A kit of parts as claimed in claim 23comprising two pipe coupling flanges, an orifice plate and a transducer,wherein the transducer is a differential pressure sensor.
 26. A kit ofparts as claimed in any of claims 23, wherein the kit of parts isassembled and tested to industry standards.
 27. (canceled) 28.(canceled)